Gene Therapy :: Genetics Science Papers

Gene Therapy: A new generation of molecular medicine In September of 1990, eight year old Ashanthi DeSilva made medical history when she received the first authorized human gene therapy treatment. Ashanthi has been born with a defective gene that normally produces an essential enzyme adenosine deaminase (ADA). If left untreated the inability to produce this enzyme results in the fatal malfunction of the immune system. Four years after receiving the first of many treatment of transgenic cells containing functional ADA genes, Ashanthi was still doing well. Since that first treatment, the National Institutes of Health (NIH) has been spending hundreds of millions of dollars to develop and evaluate new gene therapy protocols for a variety of genetic diseases (Marshall 1995). Gene therapy has made a profound impact not only in the treatment of genetic disease but also in the way that we look at human disease as a whole. The following text describes the technical and ethical aspects of gene therapy. In the final section a synthesis of the author's personal opinion is presented. 1 Technical Aspects Recombinant DNA (rDNA) technology has made the transfer of genes from one organism to another possible. The use of rDNA technology in conjunction with humans and other mammals is referred to as gene therapy. Gene therapy can be classified into two categories, germinal and somatic (Sections 1.1 & 1.2, respectively). In general, gene therapy involves augmenting the functions of an absent or dysfunctional gene by the introduction of a functional gene into the cells of the individual. If the transfer is successful, the result is a transgenic individual, who is now free of the effects of the dysfunctional gene as long as the new gene is expressed (Griffiths et al. 1996). Gene therapy has been successful in mammalian models, and potential applications for treatment of human genetic disease such as Cystic Fibrosis, ADA and various types of cancer are now being aggressively persued by researchers. Clinical trials have already begun (Section 1.4) (Kolberg 1994, Gibbs 1996 & Marshall 1995). 1.1 Germinal gene therapy Germinal gene therapy involves the introduction of genes into both somatic cells and the germline of an individual. The result is not only that the individual is cured of the genetic disease but some of the gametes of the individual may also carry the altered trait. Germinal gene therapy in mice has been successful, but thus far protocols developed for use in mice have not been effective in humans.